Scaffolds are in common use by tradesman in connection with the construction, repair, siding and painting of houses and other buildings. Such scaffolds may be suspended from the roof or upper portions of the house or building, using scaffold hangers in association with ropes and pulleys for adjustable vertical movement, or may be supported by sawhorses or temporary wooden or tubular metal structures attached to the house or building for the purpose. In nearly all cases, the platform for the scaffold consists of a number of similar long planks which are placed together side-by-side, and are supported at each end by resting upon horizontal supports, such as suspended scaffold hangers, sawhorse bars or wooden or tubular metal support structures.
In order to reduce the number of times which the scaffold must be moved, the platform is made as long as possible. Thus, planks having a length of 12 feet or 14 feet are generally used. Also, in order to reduce the effort involved in moving the scaffold, the planks used for the flooring are generally no thicker than about 2 inches. The planks used most frequently are 2".times.8", 2".times.10" and 2".times.12", each 14 feet in length.
As can be understood, scaffold platforms consisting of planks of these dimensions, supported adjacent the ends thereof, tend to bow under the weight of a worker standing near the center thereof. Such bowing generally does not present a hazard provided that all of the planks bow at the same time and to the same degree. Otherwise, the planks supporting the worker's feet bow while adjacent planks do not, thereby creating an obstacle which can cause the worker to trip. Also, if all of the worker's weight is supported by only one or two of the planks, breakage is more likely to occur.
In an effort to overcome these problems, the workmen most frequently nail one or more pieces of 1".times.3" wood board in a transverse direction across the planks on the surface of the scaffold platform, the boards being nailed to each of the planks so that the planks bow together and support each other under the weight of the worker. Such wood supports are disadvantageous because their application and removal is time-consuming; they can break or become separated during use; they are not reusable and thus are expensive; and they are relatively thick and present a tripping hazard to the worker.
Metallic cross-supports have been proposed for scaffold platforms but none of these have been commercially successful for any one of several reasons. They either consist of tubular steel which is thick and presents a tripping hazard and/or they are difficult and time-consuming to apply since they comprise long threaded members and/or they are not effective in providing adequate support to adjacent planks to resist bowing or to cause all of the planks to bow in similar manner when the weight of the worker is present on only one or two of the planks.